Method of governing prime movers.



No. 66l,222. Patented Nov. 6, I900. R. D. MERSHON.

METHOD OF GOVERNING PRIME MOVERS.

(Application filed Nov. 8, 1899.)

2 Sheets-Shoot I.

(No Iodal.)

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N0. 66l,222.' Patented NOV. 6, I900. R. D. MERSHUN.

METHOD OF GOVERNING PRIME MOVERS.

(Application filed Nov. 6, 1899.)

2 SheetSheat 2.

(No Model.)

UNITED STATES PATENT OFFICE.

RALPH D. MERSIION, OF NEW YORK, N. Y., ASSIGNOR TO THE IVESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, OF NEW JERSEY.

METHOD OF GOVERNING. PRIME MOVERS.

SPECIFICATION forming part of Letters Patent N 0. 661,222, datedNovember 6, 1900. Application filed November 6, 1899. Serial No.736,066- (No model.)

To all whmn it may concern;

Be it known that I, RALPH D. MERSHON, a citizen of the United States,residing at New York city, in the State of New York, have invented a newand useful Method of Governing Prime Movers, of which the following is aspecification, reference being had to the accompanying drawings, whichform a part hereof.

[O The governors ordinarily used for controlling prime moverssuch, forexample, as the common centrifugal governorare dependent for theiraction upon a change of speed in the prime mover; but the action of suchI5 governors is defective. In addition to the fact that they cannot actuntil the speed has changed the principle on which they are baseddemands that between no load and full load there shall be a permanentchange of speed,

2 there being for each load carried a certain speed to which the primemover must settle in order that the governor shall permit the supply ofsufficient power to carry that load. Generally the speed at full load isless than that at no load, and the difference or fall of speeddetermines the stability of regulation,

the stability being, other things equal, greater if the fall of speed isgreater and less if the fall is less. The stability of regulation ordefiniteness and steadiness with which the prime mover will assume thespeed proper to the load thrown upon it depends also upon the amount ofinertia and lost motion in the regulating and governing apparatus and3-5 upon the amount of fly wheel effect in the prime mover itself. Toomuch inertia or lost motion in the former relative to the amount ofinertia in the latter may result, when there is a change of load, in aseries of surgings 4 above and below normal speed ofprogressivelydecreasing extent. In many cases, therefore, the conditionswith a centrifugal :governor are such that the only re m edy which canbe applied for such surging is to allow the fall of speed to be greaterthan desirable or to add to the prime movera fly-whee'hwhose weight isvery objectionable. These defects in the ordinary governing apparatusare es pecially objectionable when the prime mover is used for drivingan electrical generator, :since a very uniform speed of the generator isin most cases highly desirable, and variations in speed with changes ofload greatly disturb the operation of the translating devices suppliedwith current by the generator.

It is the object of my present invention to overcome these difficultiesand to provide a governor for prime movers which is not primarilydependent for its action upon a change of speed in the motor governed byit, but which assumes a definite position for every load thrown upon theprime mover without regard to speed and in which the range of variationof speed and the amount of flywheel effect necessary for securingstability are greatly reduced.

My invention consists, broadly stated, in making use as the controllingelement of the governing apparatus of a wattmeter or powerindicatorforming part of or connected with the prime mover so as to be responsiveto changes in the load upon it; and it consists, further, in using asthe controlling element or elements of the governing apparatus such awattmeter or power-indicator in combination with a speed indicator ormeasurer connected with or actuated by the prime mover, as is morespecifically hereinafter described.

In the drawings I have shown diagrammatically forms of apparatus whichmay be used for practicing my method of regulation.

Figure 1 is a diagrammatic representation of the application of awattmeter as the controlling element of the governing apparatus for awater-wheel, steam-engine, or other prime mover. Figs. 2 and 3 arediagrammatic representations of the application of a wattmeter incombination with a speed-indicator as such controlling element, andFigs.

4 and 5 show details of construction.

The same letters of reference refer to like parts in all the drawings.

In Fig. l, W is a wattmeter actuated by the prime mover and so arrangedthat it responds directly to and indicates by means of the leverLchangesof load upon the prime mover. It may be electrical or mechanical.

Where the prime mover is used to drive an electrical generator, any ofthe ordinary forms of electrical wattmeter connected with the circuit ofthe generator, so as to indicate the amount of electrical energydeveloped in kit it, may be used as the controlling element. N in Fig. 1is intended to represent such an electrical wattmeter in one of itssimplest forms, in which S is a solenoid included in the main circuit ofthe generator D, and C is an iron core moving freely in the hollow ofthe solenoid and provided with a retractile spring R. \Vith thisarrangement the position of the core will vary with changes in thestrength of the current, and the core will thus indicate by its positionthe load upon the generator. By methods of construction and adjustmentof the solenoid and its core and the retractile spring which are wellknown in the art the core C may be made to assume and maintain adefinite position for any given load on the generator and so to indicatethe amount of electrical energy developed by it when the electromotiveforce is kept constant and the current strength alone varies. Where theelectromotive force, as well as the current strength, varies or whenapplied to an alternating-current generator, especially if the powerfactor of its load varies, a second coil 5, included in a shunt-circuitacross the terminals of the generator D, should, as is well known, heapplied to or around the core or the solenoid, so as to co operate inits magnetizing effect with the main coil. I

L is a lever pivoted to a fixed support at o. and to the core of thesolenoid at b.

M is the main supply-pipe, conveying water, for example, to awater-wheel E, used as a prime mover for driving the electricalgenerator D, and G is a gate controlling the flow of water in the pipe.

L is a lever controlling the gate G and pivoted by means of theconnecting-rod c d to the lever L. The arrangement of the levers andgate is such that the gate is opened by a downward movement of the core0 and closed by an upward movement of it.

When the prime mover is not used for driving an electrical generator orthe use of an electrical wattmeter is inconvenient or undesirable forany other reason, any of the well-known forms of transmissiondynamometer may be used as a mechanical wattmeter for the controllingelement-such, for example, as that shown in Fig. 4, where R is a shaft,P is a pulley mounted on the shaft so that it can turn freely upon it,and T is a spring one end of which is secured to the shaft and the otherto the pulley. The shaft, which is the main transmission-shaft of theprime mover, drives the pulley or is driven by it, and the tension orcompression of the spring varies with the torque transmitted, andtherefore with the load upon the prime mover. The length of the springvaries with variations in its tension or compression, and thelongitudinal position of the pulley on the shaft therefore indicates theload on the prime mover. The lever L is pivoted at a, engages by itsforked end Z with the flange t on the pulley, and so indicates thevariations in position of the shaft and the pulley and therefore theload on the prime mover. It corresponds to the lever L of Fig. 1 and isconnected to the other parts of the apparatus in the same way.

As the indicator of the wattmeter, whether electrical or mechanical,assumes and maintains a determinate position for any given load upon theprime mover, it is obvious that with the parts arranged and connected asshown in Fig. 1 the gate G will assume and maintain a determinateposition for any given load and that when there is a change in the loadthe indicator of the wattn'leter will at once assume and maintain a newposition and effect a corresponding change in the position of the gate.or valve G without waiting, as is the ca e with the ordinary governor,for a change to be effected in the speed. This results in a correctadjustment at all times of the power supplied to the prime mover to theload carried by it, provided the law of operation of the gate with themovement impressed upon it corresponds to that of the wattmeter withwhich it is connected. For exam ple, if the wattmeter employed followsthe straight-line law--that is to say, if the movement of the indicatoris directly proportional to any change in the load which itindieatesthen the corresponding movement of the gate G, if one in whichthe flow is directly proportional to the distance the gate is moved,should follow the same law; but if the wattmeter follows a lawrepresented by a curve then the corresponding movement of the gate, or,rather, its action inincreasing or decreasing the supply of water,should be made to follow alaw represented by the same curve. This resultmay be effected by properly shaping the gate or by connecting the leverby means of cams with rolling connections or irregularly-shaped gears inways which are well understood. If, for example, the core of thewattmeter shown in Fig. 1 is drawn into the solenoid decreasingdistances for equal increments of load, the levers L and L maybeconnected by a cam movement with a flexible connector :0, as shown inFig. 5, which will give the lever L a correspond ingly-increasedmovement for a given movement of the lever L. In any such arrangementthe cam must of course be shaped so as to take into account thevariation in obliquity of the various connecting-levers as well as thelaws of the wattmeter and gate.

In Fig. 2 I have shown the wattmeter of Fig. 1 combined with aspeed-indicator for controlling the position of the gate G. In this casethe wattmeter acts, as before, to open the gate G upon an increase ofload and to close it upon a decrease, and at the same time thespeed-indicator I, which I have shown as consisting of an ordinarycentrifugal governor, acts by shifting the fulcrum of the lever L toclose the gate upon an increase of speed and to open it upon a decreaseof speed. The combined action of these two devices is to adjust thesupply of power to the prime mover to the load carried by it and at thesame time to maintain a substantially uniform speed. For this purpose itisimportant that the apparatus should be so designed and adjusted thatwith the wattmeter at either limit of its movement the speed indicatoror measurer shall be able to control the power supplied. If, forinstance, the nature of the load be such that an increase of speed meansan increase of power supplied by the prime mover and if the throwing offof some of the load should produce an increase of speed, owing to thefact that it would take an appreciable time for the wattmeter to actuatethe mechanism controlling the supply of power to the prime mover,(assuming the speedindicator not to be in use,) or if there should be anincrease of speed for any other reason the speed might go on increasingindefinitely, since the wattmeter would until it reached the limit ofits movement continually call for more power as the load increased. If,however, the speed-indicator be introduced, as shown in Fig. 2, andthere be allowed a speed variation of, say, two per cent., then thespeed-indicator will be able to control the speed within the prescribedlimit and the wattmeter will be able to do its part in changing thepower supplied the instant there is any need of change by reason ofchange of load, provided the speed-indicator has sufficient control overthe powersupplied throughout the range of movement of the wattmeter toarrest acceleration of speed beyond the prescribed limits. The sameconsiderations apply to a decrease of speed due to decrease of load orany other cause.

In. Figs. 1 and 2 I have shown the controlling devices as applieddirectly to moving the gate G; but with a water-wheel of anyconsiderable size it will be necessary or at least desirable for thepurpose of securing the requisite quickness and accuracy of action tointerpose between the controlling element and the gate or nozzle someform of re lay mechanism. In Fig. 3 I have shown the use of ahydraulically-operated piston for this purpose. The lever L instead ofoperating the gate directly operates a valve V, which controls theadmission of fluid under pressure to the piston-chamber H. Water isadmitted to the valve-chamber V through the inlet-pipe J and escapesthrough the exhaust-port X. The piston P, working in the piston-chamber,is connected by means of its piston-rod Q, with the gate controlling theadmission of water .to the waterwheel. It is obvious that various otherforms of relay mechanism, mechanical or electrical, may be used, theessential feature being that all work shall, as far as possible, betaken off from the controlling element and transferred to mechanism thatis merely controlled and directed by it and that for each position ofthe governing mechanism the gate shall assume a definite predeterminedposition.

I have described my invent-ion particularly as applied to governing awater-wheel; but it is obvious that the same principles andsubstantially the same mechanism will apply to the governing of asteam-engine, a gas engine, an electric motor, or any other form ofprime mover. It may be applied either to shutting oif the supply by anordinary throttling-valve or to changing the point of cut-off.

My in vent-ion is particularly useful for governing prime movers usedfor driving electrical generators, since great constancy of speed withvariable loads is especially desirable in such cases; but it may be usedin any case where very close regulation for constant speed is desirable.

What I claim as new, and desire to secure by Letters Patent, is-

1. The method of regulating for constancy or approximate constancy, thespeed of an electric generator carrying a variable load whose variationsare due to variations in electromotive force or current or both, whichconsists in causing the electromotive force and current to produce amagnetic resultant which resultant audits variations are proportional tothe power and variations of the power delivered by the generator,causing variations in such magnetic resultant to produce correspondingvariations in the driving power applied to the generator, therebyproducing an approximately constant speed on the part of the generatorregardless of variations in the load.

2. The method of regulating for constancy or approximate constancy, thespeed of an electric generator carrying a variable load whose variationsare due to variations in elec' tromotive force or current or both, whichconsists in causing the electromotive force and current to produce amagnetic result-ant, which resultant and its variations are proportionalto the power and variations of the power delivered by the generator,causing variations in such magnetic resultant to produce independentlyof the normal operation of the speed-governor of the prime mover,corresponding variations in the driving power applied to the generator,thereby producing an approximately constant speed on the part of thegenerator regardless of variations in the load.

RALPH D. MERSHON.

Witnesses:

S. L. NICHOLSON, WM. H. OAPEL.

